Question

1. name and give a brief description of the four levels of protein structure. (2 pts)
2. what is chemical equilibrium? (3 pts)
3. if you have a glass of salt water then the salt is the __________ and the water is the __________? (1 pt)
4. if you change a protein’s structure you change its ____________ (1 pts)
5. a living cell is experiencing large fluctuations in ph. to stop those fluctuations, what would be very useful? (1 pt)
6. for each of the macromolecule groups – list their monomer, polymer, bond - type, an example, and 1 major function. (12 pts)

Explanation:

1. Primary structure: Sequence of amino - acids in a polypeptide chain.

• Secondary structure: Local folding patterns like alpha - helices and beta - sheets due to hydrogen bonding between backbone atoms.
• Tertiary structure: Three - dimensional shape of a single polypeptide chain, formed by interactions between R - groups.
• Quaternary structure: Arrangement of multiple polypeptide chains in a multi - subunit protein.

1. Chemical equilibrium is a state in a chemical reaction where the rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant over time.
2. In a salt - water solution, the salt is the solute and the water is the solvent.
3. If you change a protein's structure, you change its function, as the structure of a protein is closely related to its biological activity.
4. A buffer would be very useful to stop pH fluctuations in a living cell as buffers resist changes in pH by accepting or donating hydrogen ions.

6.

• Proteins:
• Monomer: Amino acids.
• Polymer: Polypeptide.
• Bond - type: Peptide bond.
• Example: Hemoglobin.
• Major function: Catalysis (enzymes), structural support, transport.
• Carbohydrates:
• Monomer: Monosaccharides (e.g., glucose).
• Polymer: Polysaccharides (e.g., starch, glycogen).
• Bond - type: Glycosidic bond.
• Example: Starch in plants.
• Major function: Energy storage and structural support (cellulose in plant cell walls).
• Lipids:
• Monomer: Fatty acids and glycerol (for triglycerides).
• Polymer: Lipid aggregates (e.g., triglycerides, phospholipids).
• Bond - type: Ester bond.
• Example: Triglycerides in adipose tissue.
• Major function: Energy storage, membrane structure (phospholipids).
• Nucleic acids:
• Monomer: Nucleotides.
• Polymer: DNA, RNA.
• Bond - type: Phosphodiester bond.
• Example: DNA.
• Major function: Storage and transmission of genetic information (DNA), protein synthesis (RNA).

Answer:

1. Primary structure: Amino - acid sequence. Secondary structure: Local folding (alpha - helices, beta - sheets). Tertiary structure: 3 - D shape of single polypeptide. Quaternary structure: Arrangement of multiple polypeptides.
2. State where forward and reverse reaction rates are equal, concentrations are constant.
3. Solute; Solvent
4. Function
5. Buffer
6. Proteins: Amino acids, Polypeptide, Peptide bond, Hemoglobin, Catalysis etc. Carbohydrates: Monosaccharides, Polysaccharides, Glycosidic bond, Starch, Energy storage etc. Lipids: Fatty acids and glycerol, Lipid aggregates, Ester bond, Triglycerides, Energy storage etc. Nucleic acids: Nucleotides, DNA/RNA, Phosphodiester bond, DNA, Genetic information storage etc.